Surprised no one has mentioned Melanie and “Brand New Key”. 
♫I’ve got a brand new pair of rollerskates,
You’ve got a brand new key.
I think that we should get together
And try them out, you see…♫
In a voice like an adolescent girl. 
Surprise!
Neil Young, “Harvest”:
Dream up, dream up, let me fill your cup
with the promise of a man
ZZ Top, “Pearl Necklace”, although the only real ambiguity is whether he’s talking about sex, or drugs. 
Hmm. I guess there’s a difference between double entendre and extended metaphor.
But I really like the song Passenger by Deftones. Which is not about a ride in a car.
Chrome buttons, buckles and leather surfaces
These and other lucky witnesses
Now to calm me
This time won’t you please
Drive faster
Bowser & Blue, “Polka-Dot Undies”. The entire song is a “Shaving Cream”-esque series of innuendo. The first verse:
It was probably the “o” that threw him off.
I never thought there was any ambiguity that way…
“Back Door Lover,” by “DuJour” from Josie and the Pussycats
“Firing the Surgeon General,” by the Foremen
“Feed My Frankenstein,” by Alice Cooper
Hold it - what?!?
“The Cutest Little Dinghy in the Navy” Ruth Wallis - The Dinghy Song Lyrics | SongMeanings
Benny Bell - Shaving Cream (later made re-famous by Dr. Demento, who then did his own version, natch).
Look, I already have enough people telling me I’m obsessed with anal sex, without you chiming in.
I’d call that a euphemism rather than a double entendre.
I’d call that wrong.
I don’t think he is. “Shaving cream” is being used as a polite fill in for “shit.” There’s no double meaning that can be read into as there is, for example, with a lock and key being a vagina and penis.
These were 2 of the 3 I thought of first
The third is older, Rosemary Clooney’s Come On-A My House